Method of agglomeration



Dec. 30, 1952 M. c. JEAN ET AL 2,623,243

METHOD OF AGGLOMERATION Filed Jan. 8, 1947 INVENTORS RolmrbLLAl/REN TJacques LELO/V' Hand. C JEAN AT T0 iz/vsm Patented Dec. 30, 1952 v2,623,243 METHOD OF AGGLOMERATION Marcel 0. Jean, Paris, Jacques Lelong,Rouen, and

Robert L. Laurent, Saint Hilaire, France, assignors to Societe Chimiquede la Grande Paroisse, Azote et Produits Chjmiques, Paris, France, acompany of France Application January 8, 1947, Serial No. 720,870 InFrance January 9, 1946 Claims. 1

When it is desired to produce the self agglomeration of pulverulentmaterial with a view to obtaining agglomerated material adapted to besubmitted to sub-sequent'handling without any exaggerated crumblingaway, it is generally necessary either to operate with the highagglomerating pressure of the magnitude of 1,500 kgs. per sq. cm. in thecase of lignite or bituminous coal or else to resort to costly orobjectionable binders such as pitch or cement.

These methods show the drawback of bein comparatively costly whichprevents them from being used when it is desired to agglomerate rawmaterial of low value such as the pulverulent residue of bituminousschist or the like material.

For this reason, attempts have been generally to this day given up asconcerns the use of such dust which leads to a waste reaching as high asto of the production of schist.

Our present invention has for its object to remove these drawbacks andto allow agglomeration through extremely cheap means requiring only verysmall plants, of dust of any kind and in particular of bituminousschist, lignite, coal and the like dust.

We have found that it was possible to obtain a satisfactory selfagglomeration without any binder through a rapid compression atcomparatively low pressures, provided the pulverulent material has beenpreviously treated so that there remains in said material neither anysuperficially absorbed gases nor occluded gases at the moment of theagglomerating compression. It is chiefly the presence of such gases andin particular of absorbed gases even in small amounts which as a matterof fact prevents the agglomeration as these gases are compressed duringthe shaping and their expansion at the moment of the subsequentreduction in pressure leads to a disaggregation of the moulded products.

In accordance with our invention, the gases which are superficiallyabsorbed or occluded inside the material before it is compressed foragglomeration, are removed by submitting the material to a uniformheating to a sufficient extent preferably in the presence of water or ofsteam. We inject for instance steam into the product until the wholemass is heated uniformly to a temperature approximating 90 or 100 C. Wemay also according to our invention heat the product in a moist state soas to bring it to the vicinity of 100 C.

The product to be compressed should however not be too moist at themoment of compression. The possible rate of moisture allowable dependsmoreover on the nature of the product. Moisture contents of 8% which area hindrance to the agglomeration of certain salts such as ammoniumchloride are still allowable in the case of lignite or fibrous material.

Furthermore, according to our invention, it has been found that betterresults are obtained when the pulverulent material such for instance ascoal, lignite, bituminous schist, and the like is crushed so as toinclude grains of difierent sizes in proportions such that the intervalbetween grains of similar size may be filled up in practice by finergrains without leaving any substantial empty space.

The product to be submitted to agglomeration should include for instance25 to 30% of powder passing through a sieve of 200 mesh, per inch and asubstantially equal proportion of grains passing between 50 and 200mesh, the remainder being formed by grains having a diameter comprisedbetween 0.5 and 3 mm.

It is however of no advantage to prosecute the crushing down to anextreme fineness, it has been in fact recognised that the extremelylight particles or very light meal produce with much more difficultycompact agglomerates when it is desired to agglomerate them alone.

We have illustrated diagrammatically by Way of example in accompanyingdrawing an arrangement for the practical execution of a method accordingto our invention and applicable in particular to the agglomeration offines of bituminous schist with a view to their subsequent pyrogenationin a furnace provided with a circulation of hot gases.

The fine grains passing through the 6 mm. mesh and consequently too fineto be admitted as such in the pyrogenation furnace are fed through aconveyor belt I on to a vibrating sieve 2 provided with canvas showing 3mm. meshes. The fractions which do not pass through said sieve andcorresponding to about 25% of the fines flow out at 3 into a hopper outof which they pass into a hammer crusher 5 producing about 50% of aproduct underneath the 200 mesh size and only 25% of a product of the 80mesh size.

This fine product is blown by a fan 9 into a hopper l0. The fines fromthe sieve 2 and hopper 8 forming about of the total are disclosedhereinabove and also the fines fed by the hopper I0 which form about 25%of the total are fed respectively through the worm conveyors II and 12to a mixer I 3 adapted to heat and moisten the mixture and at the lowerend of which there is injected through a pipe l4 steam the weight ofwhich is about 5% of the weight of the fines being treated, which leavesthe product treated at about 100 C. This treated moistened product isthen brought directly to a ball press l5 which forms agglomerated cakesof tetrahedric shape weighing about twenty grams and which may be loadeddirectly into a pyrogenation furnace together with the raw calibratedbituminous schist. It is important that the dust particles may beintroduced into the ball press immediately after their treatment throughsteam so that they may not be aerated again.

The ball press used may be a press of any ordinary type producingpressures of the magnitude of only a few hundred kgs. per sq. cm.

Cylindrical agglomerates of 27 mm. prepared under such conditions andsubmitted to tests 01' resistance against crushing could bear'pressures.of 38 kgs. per sq. cm. They could be sumitted without any .difficulty topyrogenation and after pyrogenation at 500 C. they could .be submittedto a pressure of 60 kgs. persq. cm.

Obviously many modifications may be brought to the above describedmethods; in particular, it is possible to mix directly the dust withwater and to heat it to the desired temperature so that the steamproduced may excel the occluded gases.

Moreover our invention is by no means limited to the treatment ofbituminous schist dust and it is applicable as well to the agglomerationofany dust including pulverulent lignite, coal, and even ammoniumchloride etc.

What we claim is:

1. A method for agglomerating fines of bituminous schists, oil shalesand the like oil-containing rocks, consisting in sizing the fines toform a mixture, containing no grains above 8 millimeters, removing theabsorbed and occluded gases from said fines and submitting the mixtureto a sudden pressure of the magnitude of not substantially above 100 kg.per sq. cm. at a temperature below 100 C.

2. A method for agglomerating fines of bituminous schists, oil shalesand the like oil-containing rocks, consisting in sizing the fines toform a mixture, containing no grains above 3 millimeters maintaining themoisture of said fines less than about 8%, injecting steam inside themixture of fines for degasifying same. and submitting the mixture to asudden pressure of the magnitude of not substantially above 100 vkg. persq. cm. at a temperature below 100 C.

3. A method for agglomerating fines of bituminous schists, oil shalesand the like oil-containing rocks, consisting in sizing the fines mixingfines of different sizes to form a mixture showing only very reducedempty spaces, containing no grains above 3 millimeters maintaining themoisture of said fines less than about 8%, removing the absorbed andoccluded gases from said fines and submitting the mixture to a lowpressure of a few hundred kg. per sq. cm. at a temperature below C.

4'. A method for agglomerating fines of bituminous schists, oil shalesand the like oil-containing rocks, consisting in sizing the fines mixinsfines of different size to form a mixture showing only very, reducedempty spaces, containing no grains above 3 millimeters, mixing the fineswith water, heating same for expelling the occluded and absorbed gasesthrough the steam produced, and submitting the mixture to a suddenpressure of the magnitude of not substantially above 100 kg. per sq. cm.at a temperaturebelow 100 C.

5.. A method for agglomerating fines of bituminous schists, oil shalesand the like oil-containing rocks, consisting in sizing the fines mixingfines of difierent size to form a mixture showing only very reducedempty spaces, containingno grains above 3 millimeters maintaining themoisture of said fines less than about 8%. removing the absorbed andoccluded gases from said fines and agglomeratingthe. mixture incomparatively small-sized units through the rapid application of a lowuniformly distributed pressure at a temperature below 100 C.

MARCEL C. JEAN.

JACQUES LELONG.

ROBERT L. LAURENT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED. STATES PATENTS Number Name Date 874,167 Crow Dec. 17, 19071,453,983 Mueller May 1, 1923 1,466,571 Thorssell et al. Aug. 28, 19231,503,907 Maignen Aug. 5, 1924 1,528,851 Rodling et al. Mar. 10, 19251,751,430 Thomson Mar. 18, 1930 1,796,465 Komarek Mar. 17, 19311,891,893 Spengler et al. Dec. 20, 1932 2,283,364 Hanson et al. May 19,1942 2,304,382 Shoeld Dec. 8, 1942 2,424,012 Bangham et al. July 15,1947

1. A METHOD FOR AGGLOMERATING FINES OF BITUMINOUS SCHISTS, OIL SHALESAND THE LIKE OIL-CONTAINING ROCKS, CONSISTING IN SIZING THE FINES TOFORM A MIXTURE, CONTAINING NO GRAINS ABOVE 3 MILLIMETERS, REMOVING THEABSORBED AND OCCLUDED GASES FROM SAID FINES AND SUBMITTING THE MIXTURETO A SUDDEN PRESSURE OF THE MAGNITUDE OF NOT SUBSTANTIALLY ABOVE 100 KGPER SQ. CM. AT A TEMPERATURE BELOW 100* C.